1. Field of the Invention
This invention relates generally to display devices, and relates more particularly to an apparatus and method for handling special windows in a display.
2. Description of the Background Art
Effective presentation of visual information is an important consideration for manufacturers, designers, and users of displays. Such displays are commonly used for interfacing with computers. Many modern computer operating systems use graphical user interfaces that enclose information from application programs in separate viewing areas or windows in a display to simplify information management.
These special windows in a display may be used for presentation of different types of information than are typically shown in the remainder of the display. In some applications, use of a special window in a display may be desirable to help distinguish or differently process information. For example, a computer system may present video information from a video source (such as a video camera or video tape recorder) in a special window, while simultaneously presenting more traditional computer-generated information such as text and graphics in the rest of the display.
Conventional computer displays are designed to present text and graphics, but are not specifically designed to present video information. Luminance levels in conventional computer displays are usually considerably lower than the luminance levels used in conventional video monitors or television screens. Video information presented in conventional computer displays thus appears to have less contrast between bright and dark areas, and tends to look rather murky. Raising luminance levels is one possible way to enhance the presentation of video information in computer displays, but problems may arise from indiscriminately raising luminance levels over the entire display surface.
For example, text or graphics outside the special window may become blurred, decreasing the overall effectiveness of the display. Furthermore, continuously raising luminance levels over the entire display surface may unacceptably accelerate the aging of the display tube. These problems could be avoided with an effective means for identifying and locating the limited portions of a special display window to be advantageously processed.
The coordinates of a special display window may be transmitted to a display via a separate data channel. For example, the serial interface available on most modern computers may be dedicated to this purpose. However, this potential solution presents a number of difficulties. First, such a system would demand significant additional hardware within a computer system; a second serial interface card would have to be managed by the computer system. Second, the signals generated by such serial interface hardware would have to be precisely calibrated with the horizontal and vertical video synchronization signals going to the display. Finally, significant software development would be required to coordinate such a dual-channel interface system.
Therefore, for the foregoing reasons, an improved apparatus and method for handling special windows in a display is needed, in accordance with the present invention.